This invention relates to an electromechanical clutch for an engine cooling fan.
Experience has conclusively demonstrated that operation of the engine cooling fan is necessary only during a relatively small percentage of the time that a vehicle engine is operated. If the fan is driven when it is not necessary, the power used to rotate the fan is wasted, thereby increasing gasoline consumption. Accordingly, it is desirable to provide a fan clutch which disconnects the cooling fan during certain engine operating conditions. Such a fan clutch design is disclosed in my prior U.S. patent application Ser. No. 900,829, filed April 28, 1978, assigned to the assignee of the present invention and incorporated herein by reference. This device disclosed in my prior patent application uses an electromagnetic coil which, when energized, draws a magnetic band into driving engagement with the driven member to thereby transmit torque to the driven member which carries the cooling fan. Although the device disclosed in this prior application works quite well, it is desirable to assure that any slippage that occurs between the various components upon engagement of the clutch be properly accommodated, since such slippage in certain instances can cause premature wear of some of the components.